Roof structure

ABSTRACT

The present invention relates to a roof structure. The structure comprises support members defining openings. Bridge members extend between the support members. End portions of the bridge members are able to be received by the openings in the support members such that the end portions can be inhibited from being withdrawn from the openings. A safety barrier is supported by the bridge members. The structure also comprises an insulating layer including insulation pockets and being supported by the safety barrier.

FIELD OF THE INVENTION

The present invention relates generally to a building roof structure.The present invention also relates to a method of building a roofstructure.

BRIEF DISCUSSION OF THE PRIOR ART

The reference to any prior art in this specification is not, and shouldnot be taken as an acknowledgement or any form of suggestion that theprior art forms part of the common general knowledge.

A typical building roof structure includes a plurality of supportmembers and a roofing layer which is secured to and supported by thesupport members. The support members are typically provided by purlinswhich are secured to one or more rafters, and the roofing layer isusually provided by a plurality of tiles, roof panels, shingles, or thelike which are secured to and supported by the purlins.

Sometimes the roof structure will include a fall protection system forpreventing a person or other objects from falling through the roofstructure. The fall protection system typically comprises a safetybarrier in the form of safety mesh or the like which is placed on top ofthe purlins and which is secured to the purlins.

A layer of thermal insulation is often included in the roof structure toinhibit the transfer of heat through the roof structure. The layer ofinsulation is typically placed on top of the purlins, and the roofinglayer is then placed on top of the insulation. This tends to compressareas of the insulation which are located between the roofing layer andthe purlins.

Compressing the insulation can be problematic in that the compressedareas of the insulation usually do not perform at an optimum level. Inother words, compressing the insulation can compromise the thermalinsulating properties of the insulation. If the performance of theinsulation is compromised, the energy efficiency of the building can beimpaired so that more energy is required to cool or heat the interior ofthe building to maintain it at a desired temperature.

In order to improve the energy efficiency of new buildings, Section J ofthe Building Code of Australia (“BCA”) was introduced by the AustralianBuilding Codes Board. Section J of the BCA requires the roof structureof a new building to have a minimum R-value of 3.2, and stipulates that,in order to achieve this, there must be a recovery air gap between theroofing layer and the insulation so that the insulation is notcompressed between the purl ins and the roofing layer.

U.S. Pat. No. 4,047,346 (Alderman) and U.S. Pat. No. 4,379,381(Holcombe) disclose thermally insulated roof structures which include anair gap between a roofing layer and a thermal insulation layer.

Alderman discloses an insulated roof structure formed on an industrialbuilding by mounting a support framework on the purlins of the partiallycompleted roof structure and moving the framework along the length ofthe purlins. A reel of wire mesh and a reel of sheet material arecarried by the framework over each of the spaces between adjacent onesof the purlins, and the reels are progressively unrolled, and the layersof wire mesh and sheet material are applied to the spaces between thepurlins as the support framework moves. Additional insulation can beblown upon or otherwise applied to the sheet material to fill the spacesbetween the purlins, and hard sheets of roofing material are applied tothe purlins as the support framework progresses across the structure.

A central web of each purlin of the insulated roof structure disclosedby Alderman includes a plurality of openings. The roof structure alsoincludes a plurality of support straps. Each support strap is threadedthrough one of the openings in each purlin. The support strap is placedunder tension so that it extends in a substantially flat plane betweenadjacent ones of the purlins.

Being straps, the support straps are quite flexible. Consequently, thesupport straps are not particularly well-suited to spacing the purlinsapart from each other, or to maintaining the spacing between thepurlins.

Each of the support straps is inhibited from being withdrawn from theopening through which it extends by a retaining clip which is wedged inthe opening so as to form a friction connection between the purlin andthe support strap.

The layers of wire mesh which are applied to the spaces between thepurlins are placed on the support straps. The support straps support themesh at spaced intervals along the lengths of the purlins, and tensionis applied to the mesh so as to prevent the mesh from saggingextensively between adjacent ones of the support straps.

The sheet material is placed upon the mesh, and a quantity of heatinsulation material is disclosed inserted in the spaces between adjacentones of the purlins and onto the sheet material. The insulation materialcan be in the form of blocks of solid material, sheets of material,loose material, or material that was initially loose when placed in thespace but sprayed or otherwise mixed with adhesive as or after beinginserted into the spaces so as to become substantially rigid.

An additional sheet of insulation material is applied to the top surfaceof the upper flange of each of the purlins, and the hard sheets ofroofing material are placed on the sheet insulation material andconnected to the purlins by self-tapping screws or other fasteners.

The additional sheet of insulation material functions to reduce thetransfer of heat between the hard sheets of roofing material and thepurlins, and the insulation material in the spaces between adjacent onesof the purlins function to inhibit the transfer of heat between insidethe building and the hard sheets of roofing material by means ofconvection and radiation.

FIG. 1 of Alderman depicts an air gap which separates the sheets ofroofing material from the heat insulation material which is supported bythe sheet material.

Holcombe discloses an insulation system for a roof structure whichincludes a semi-rigid insulation blanket overlying a support structureacross roof purlins and having additional insulation material filling aU-shaped trough created by the blanket between adjacent purlins. Thesemi-rigid insulation blanket is notched by the manufacturer atpredetermined points to enable the blanket to easily and securely foldover and around the support structure and roof purlins.

The support structure of the Holcombe insulation system includes mainsupport brackets which extend between and rest on top of the purlins,and longitudinal support brackets which extend between and rest on topof the main support brackets. The main support brackets and thelongitudinal support brackets include fastening holes for receivingplastic snap-in fasteners which secure the main support brackets to thepurlins and which secure the longitudinal support brackets to the mainsupport brackets.

FIG. 2 of Holcombe depicts an air gap separating the roof panel and aninsulation bat of the roof structure.

It would be desirable to provide bridge and support members for a roofstructure which are able to be secured together in a different manner tothe bridge and support members of the aforementioned prior art roofstructures.

Also, it would be desirable to provide a roof structure which includes aplurality of the aforementioned bridge and support members. It would bedesirable for the roof structure to incorporate a fall protectionsystem. It would also be desirable for the roof structure to comply withSection J of the BCA.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, there is provided aroof structure comprising:

support members defining openings;

bridge members extending between the support members, end portions ofthe bridge members able to be received by the openings in the supportmembers such that the end portions can be inhibited from being withdrawnfrom the openings;

a safety barrier supported by the bridge members; and

an insulating layer including insulation pockets and being supported bythe safety barrier.

The insulation pockets may be arranged in a cellular manner between apair of sheets. The sheets may be metallic foil sheets. The sheets mayinclude reflective aluminium foil. The insulation pockets may be sealedair or foam pockets. The insulating layer may rest directly on thesafety barrier.

According to another aspect of the present invention, there is provideda method of building a roof structure, the structure having bridgemembers extending between support members such that end portions of thebridge members are received by openings in the support members and theend portions can be inhibited from being withdrawn from the openings,the bridge members supporting a safety barrier, the method comprisingthe step of:

providing an insulating layer defining insulation pockets on the safetybarrier.

According to another aspect of the present invention, there is provideda method of building a roof structure, the method comprising the stepsof:

extending a plurality of bridge members laterally between a plurality ofadjacent support members such that end portions of the bridge membersare received by openings in the support members and the end portions canbe inhibited from being withdrawn from the openings;

supporting a safety barrier with the bridge members; and

supporting an insulating layer defining insulation pockets with thesafety barrier.

According to another aspect of the present invention, there is providedan insulating layer including insulation pockets when used in a roofstructure that has bridge members extending between support members,with end portions of the bridge members being received by openings inthe support members and with the end portions being inhibited from beingwithdrawn from the openings, the bridge members supporting a safetybarrier on which the insulating layer can be located.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the invention may be more fully understood and put intopractice, a preferred embodiment thereof will now be described withreference to the accompanying drawings, in which:

FIG. 1 is a perspective view of a roof structure according to apreferred embodiment of the present invention;

FIG. 2 is a perspective view of a bridge member of the roof structure;and

FIG. 3 is an end view of the roof structure;

FIG. 4 is a perspective view of a telescopic bridge member of a roofstructure in accordance with another embodiment of the present inventionwith parts separated;

FIG. 5 is a perspective view of the telescopic bridge member of FIG. 4with parts engaged;

FIG. 6 is a top view of the telescopic bridge member of FIG. 5;

FIG. 7 is a side view of the telescopic bridge member of FIG. 5;

FIG. 8 is a bottom view of the telescopic bridge member of FIG. 5;

FIG. 9 is an end view of the telescopic bridge member of FIG. 5;

FIG. 10 is a partial perspective view of the telescopic bridge member ofFIG. 5 engaging with a purlin; and

FIG. 11 is a side sectional view of alternate insulating material to beused in the roof structure of FIG. 1, in accordance with an embodimentof the present invention.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring to the figures, a roof structure 20 according to a preferredembodiment of the present invention comprises a plurality of adjacentsupport members in the form of purlins 21. Purlins 21 are parallel toeach other, and are spaced apart from each other at regular or irregularintervals.

Each purlin 21 is made from sheet metal, and has a Z-shaped profilecomprising a lower portion in the form of a lower panel 22, an upperportion in the form of an upper panel 23, and a vertical intermediateportion in the form of an intermediate panel 24 which extends betweenthe lower panel 22 and the upper panel 23, and which is perpendicularwith respect to the lower panel 22 and the upper panel 23. A lip 25extends upwardly from the lower panel 22, and is perpendicular withrespect to the lower panel 22. A lip 26 extends downwardly from theupper panel 23, and is perpendicular with respect to the upper panel 23.

A plurality of T-shaped openings 27 are punched into the intermediatepanel 24 of each purlin 21. Openings 27 are spaced apart from each otherat regular intervals along the length of the purlins 21. FIG. 1 onlyshows one of the openings 27 in each of the purlins 21. Each opening 27includes a first portion 28 and a second narrower portion 29 whichadjoins the first portion 28.

A plurality of bridge members 30 are spaced apart from each other atregular intervals and extend laterally between each pair of adjacentpurlins 21 such that the bridge members 30 are perpendicular withrespect to the purlins 21.

Each bridge member 30 is made from sheet metal, and includes anintermediate portion 31 and a pair of end portions 32 which extend fromthe intermediate portion 31. Intermediate portion 31 includes a toppanel 33 and a pair of side panels 34 which extend perpendicularly fromthe top panel 33. Each end portion 32 is provided by the top panel 33,and includes a head portion 35 and a narrower neck portion 36 whichextends from the head portion 35.

The end portions 32 of the bridge members 30 are each received by theopenings 27 in the purlins 21. The side panels 34 of each bridge member30 are supported by the lip 25 of one of the purlins 21 which the bridgemember 30 extends between.

In order to insert the end portion 32 of a bridge member 30 into one ofthe openings 27, the head portion 35 and the neck portion 36 of the endportion 32 are inserted into the first portion 28 of the opening 27 sothat the neck portion 36 is located above the second portion 29 of theopening 27. The neck portion 36 is then lowered into the second portion29. The width of the second portion 29 is such that the head portion 35is inhibited from being withdrawn from the opening 27.

The end portion 32 is able to be removed from the opening 27 by firstlyraising the end portion relative to the opening 27 so that the neckportion 36 is located in the first portion 28. The head portion 35 andthe neck portion 36 are then able to be withdrawn from the first portion28 of the opening 27.

Each opening 27 is able to receive an end portion 32 of two bridgemembers 30 as shown in FIGS. 1 and 3. The end portion 32 of one of thebridge members 30 which is received by a particular opening 27 overliesthe other bridge member 30 which is received by that opening 27. Inparticular, the head portion 35 of the overlying end portion 32 lies ontop of the top panel 33 of the other bridge member 30 which is receivedby the opening 27. The end portions 32 of the two bridge members 30which are received by the opening 27 are secured together with fastenerswhich are in the form of 12×25 “Tek” screws 37.

A safety barrier 40 for preventing a person from falling off the roofstructure 20 is secured relative to the bridge members 30 of the roofstructure 20 as shown in FIGS. 1 and 3. Barrier 40 comprises a pluralityof individual safety wires 41 which extend between adjacent bridgemembers 30. Wires 41 are secured to the bridge members 30 by wrapping orlooping their ends around the bridge members 30 and then twisting theends around the wires 41 as depicted in FIG. 1.

The bridge members 30 and the safety barrier 40 support an insulatinglayer which is provided by thermal insulation 42. Insulation 42 may beany suitable type of insulation. For example, insulation 42 may befibreglass or wool insulation.

A roofing layer provided by one or more ribbed roof panels or sheets 50is supported by the purlins 21 such that the sheets 50 rest on the upperpanels 23 of the purlins 21. Roof sheets 50 and the insulation 42 areseparated from each other by an air gap 60 which is 100 mm wide.

A method of building the roof structure 20 is now briefly described. Themethod comprises the steps of:

(i) extending a plurality of bridge members 30 laterally between aplurality of adjacent purlins 21 such that the end portions 32 of thebridge members 31 are received by the openings 27 in the purlins 21 suchthat the end portions 31 can be inhibited from being withdrawn from theopenings 27;

(ii) supporting the safety barrier 40 with the bridge members 30;

(iii) supporting the insulating layer 42 with the safety barrier 40; and

(iv) supporting the roofing layer 50 with the purlins 21 such that theroofing layer 50 and the insulating layer 42 are separated from eachother by the air gap 60.

Turning to FIG. 4, each bridge member 30 can be replaced by a telescopicbridge member 60 including two generally C-shaped body parts 62, 64 (seealso FIG. 9). The bridge member 60 is substantially rigid and comprisesan intermediate portion formed by the overlapping body parts 62, 64, anda pair of end portions 32 located at opposite ends of the intermediateportion. Each end portion 32 (as previously described) is adapted to bereceived by an opening 27 in a purlin 21 such that the end portion 32can be inhibited from being withdrawn from the opening 27. The rigidbridge members 60 can be used to space a plurality of the purlins 21apart from each other at regular intervals, and for maintaining thespacing between the purlins 21.

Each body part 62, 64 is of a similar construction. However, as can bestbe seen in FIGS. 5 to 8, body part 64 is dimensioned so as to be snuglyslid within body part 62. Body part 64 defines a threaded fastening hole66 for receiving a grub screw to fixedly fasten the movable parts 62, 64together. In addition, one of the end portions 32 may define anotherfastening hole 68 in which a “Tek” screw 37 can be received whenfastening end portions 32 of serially arranged bridge members 60together.

Turning to FIG. 10, there is provided another purlin 70 with anintermediate panel 72. The purlin 70 is rotationally symmetric anddefines a pair of symmetric openings 74 a, 74 b so that the purlin 70has the same characteristics when mounted in either orientation, 180°apart. Each opening 74 defines a central portion 76 through which an endportion 32 is initially received. A pair of walls 78 taper downwardly toguide the neck portion 36 of the bridge member 60, and resilientlyreciprocate to lock the bridge member 60 in a bottom recess 80 of theopening 74.

The bulk fibreglass or wool insulation 42 shown in FIG. 1 iscomparatively difficult to install, and heavy which can cause the wires41 of the safety barrier 40 to sag. Alternatively, using a thin andlight-weight insulating layer 42 a air-cell insulation produced byKingspan™, as shown in FIG. 11, reduces sagging of the safety barrier 40and is comparatively simple to install being supplied on a roll. Acomparatively larger air gap results, and using the insulating layer 42a also produces a satisfactory thermal resistance value (Rvalue).

Turning to FIG. 11, the insulating layer 42 a includes insulation airpockets 90 which are arranged in a cellular array between a pair ofhighly reflective aluminium foil sheets 92 a, 92 b. The insulationpockets 90 typically contain sealed air or, in another embodiment,insulating foam.

A method of building the roof structure 20 using insulating layer 42 ais greatly simplified. The method involves providing the insulatinglayer 42 a on the safety barrier 40 from its roll.

Throughout the specification and the claims, unless the context requiresotherwise, the term “comprise”, or variations such as “comprises” or“comprising”, will be understood to apply the inclusion of the statedinteger or group of integers but not the exclusion of any other integeror group of integers.

Throughout the specification and claims, unless the context requiresotherwise, the term “substantially” or “about” will be understood to notbe limited to the value for the range qualified by the terms.

It will be appreciated by those skilled in the art that variations andmodifications to the invention described herein will be apparent withoutdeparting from the spirit and scope thereof. The variations andmodifications as would be apparent to persons skilled in the art aredeemed to fall within the broad scope and ambit of the invention asherein set forth.

It will be clearly understood that, if a prior art publication isreferred to herein, that reference does not constitute an admission thatthe publication forms part of the common general knowledge in the art inAustralia or in any other country.

The foreign priority application, Australian application 2013200319,filed Jan. 22, 2013, is incorporated by reference herein.

The claims defining the invention are as follows:
 1. A roof structurecomprising: support members defining openings; bridge members extendingbetween the support members, end portions of the bridge members able tobe received by the openings in the support members such that the endportions can be inhibited from being withdrawn from the openings; asafety barrier supported by the bridge members; and an insulating layerincluding insulation pockets and being supported by the safety barrier.2. A roof structure as claimed in claim 1, wherein the insulationpockets are arranged in a cellular array between a pair of sheets.
 3. Aroof structure as claimed in claim 2, wherein the sheets are metallicfoil sheets.
 4. A roof structure as claimed in claim 3, wherein thesheets include reflective aluminium foil.
 5. A roof structure as claimedin claim 1, wherein the insulation pockets are sealed air or foampockets.
 6. A roof structure as claimed in claim 1, wherein theinsulating layer rests directly on the safety barrier.
 7. A roofstructure as claimed in claim 6, further including a roofing layer beingsupported by the support members, the roofing layer and the insulatinglayer being separated from each other by an air gap.
 8. A roof structureas claimed in claim 1, wherein each bridge member is substantially rigidand comprises an intermediate portion, and a pair of end portionslocated at opposite ends of the intermediate portion.
 9. A roofstructure as claimed in claim 8, wherein each of the end portionsincludes a neck portion which extends from the intermediate portion andcan receive a support member, and a head portion which extends from theneck portion and which is wider than the neck portion to inhibitwithdrawal of the end portion from an opening.
 10. A roof structure asclaimed in claim 8, wherein the intermediate portion includes a mainpanel, and a pair of side panels extending from opposite sides of themain panel, the end portions being coplanar with the main panel.
 11. Aroof structure as claimed in any one of claims 8, wherein theintermediate portion is generally C-shaped.
 12. A roof structure asclaimed in claim 1, wherein each opening includes a first portion whichallows the end portions of the bridge members to be inserted into andremoved from the opening, and a second narrower portion which adjoinsthe first portion and which is able to inhibit the end portions frombeing withdrawn from the opening.
 13. A roof structure as claimed inclaim 12, wherein the openings of the support members are T-shaped andthe support member is either a purl in or a rafter.
 14. A roof structureas claimed in claim 12, wherein the profile of the support memberincludes a lower panel and an upper panel which are co-parallel, and anintermediate panel extending perpendicularly between the lower panel andthe upper panel.
 15. A roof structure as claimed in claim 1, wherein:the bridge members supporting the safety barrier extend between lowerportions of the support members; each support member is a purlin, andthe purlins can be pulled toward each other by the bridge members ifsufficient downward force is applied to bend the bridge members; eachbridge member is telescopic so that its length can be varied; or the endportions of the bridge members are T-shaped.
 16. A method of building aroof structure, the structure having bridge members extending betweensupport members such that end portions of the bridge members arereceived by openings in the support members and the end portions can beinhibited from being withdrawn from the openings, the bridge memberssupporting a safety barrier, the method comprising the step of:providing an insulating layer defining insulation pockets on the safetybarrier.
 17. A method of building a roof structure, the methodcomprising the steps of: extending a plurality of bridge memberslaterally between a plurality of adjacent support members such that endportions of the bridge members are received by openings in the supportmembers and the end portions can be inhibited from being withdrawn fromthe openings; supporting a safety barrier with the bridge members; andsupporting an insulating layer defining insulation pockets with thesafety barrier.
 18. A method of building a roof structure as claimed inclaim 16, wherein the insulating layer includes a pair of metallicsheets between which the insulation pockets are located.
 19. A method ofbuilding a roof structure as claimed in claim 16, further comprising thestep of: supporting a roofing layer with the support members such thatthe roofing layer and the insulating layer are separated from each otherby an air gap.
 20. A method of building a roof structure as claimed inany one of claim 16, wherein: each bridge member is substantially rigidand comprises an intermediate portion, and a pair of end portionslocated at opposite ends of the intermediate portion, each end portionbeing adapted to be received by an opening in a support member of theroof structure such that the end portion can be inhibited from beingwithdrawn from the opening; and each support member comprising aplurality of openings that are each adapted to receive an end portion ofa bridge member such that the end portion of the bridge member can beinhibited from being withdrawn from the opening.